New Zealand Journal of Geology & Geophysics abstracts
Olistostromes marking tectonic events, East Coast, New Zealand
J. Delteil1
B. Mercier de Lepinay1
H. E. G. Morgans2
B. D. Field2*
1Geosciences Azur
UMR 6526
Universite de Nice - Sophia Antipolis
250 Rue Albert Einstein, Sophia Antipolis
F-06560 Valbonne, France
2GNS Science
PO Box 30368
Lower Hutt 5040, New Zealand
*Corresponding author: brad.field@gns.cri.nz
Abstract Three discrete, successive tectonic
events are
marked by olistostromes in the East Coast, North Island. An Eocene
Mataikona event is characterised by in situ dismembered beds. A
second, Owahanga event is Otaian and preceded wrench faulting coeval
with the start of oblique subduction at the East Coast margin. This
second event is characterised by extended emplacement of exotic
material followed by gliding, gravity-driven nappes that are probably
related to obduction along the north coast of the North Island. The
third olistostrome is attributed to an early Miocene Mara event
synchronous with incipient strike-slip faulting during Altonian times
and the commencement of oblique convergence at the Hikurangi margin.
From the ages and paleoenvironments of the olistostromes, we propose
the Eocene and earliest Miocene syn-sedimentary structures were dragged
along the deforming backstop of the Hikurangi prism.
Keywords melanges; olistostromes; Cenozoic;
oblique
convergence; deforming backstop
G06013; Online publication date 4 December 2006; Received 12 June
2006; accepted 28 November 2006
New Zealand Journal of Geology & Geophysics, 2006, Vol. 49:
517–531
0028–8306/06/4904–0517 © The Royal Society of New Zealand
2006
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